1. Field of the Invention
The present invention relates to a method of monitoring washing water used in developing a photosensitive material. In the method, washing water is stored in a washing tank, which is one of a plurality of processing tanks for processing a photosensitive material such as photographic film. The washing water is monitored so as to determine the degree of mixing of the water with a processing solution or processing solutions used in preceding stages. (Processing solution(s) in the processing tank(s) are located on the upstream side of the washing tank in the direction of flow of the photosensitive material.) The mixture of the processing solution(s) in the washing water occurs due to processing of the photosensitive material.
2. Description of the Related Art
In a developing process, a photosensitive material is successively immersed into various processing solutions such as a color developing solution and a bleaching/fixing solution, and is then washed with water before being transported to a drying section.
In general, a plurality of washing tanks storing washing water are provided to wash a photosensitive material. Since processing solutions which have adhered to a photosensitive material in preceding stages are gradually removed from the material in the plurality of washing tanks, the degree of contamination (especially, the degree of mixing of a bleaching/fixing solution) is relatively small in the final washing tank. However, it is sometimes observed, after repeated development, that the bleaching/fixing solution has been mixed into the washing water in the final washing tank.
This mixing is caused by processing solutions transported by the photosensitive material, as well as by water drops containing agents which adhere to a ceiling of a laboratory due to evaporation of processing solutions and then fall into the washing tanks.
In a so-called mulch-chamber washing tank in which a washing tank is divided into upper and lower tanks and the upper tank is further divided into left-hand and right-hand tanks, contamination of washing water in the final washing tank proceeds quickly if washing water leaks through an opening formed in each partition for a photosensitive material. Although each partition is provided with blades and rollers for separating washing tanks on both sides thereof, a considerable leak may occur due to a mechanical malfunction.
A known technique is to replenish fresh water in the washing water when the degree of contamination exceeds a predetermined value. However, published documents disclose neither means for detecting the degree of contamination, nor control based on the detected degree of contamination. Accordingly, the problem of contamination of washing water is usually avoided by replenishing fresh water or replacing the washing water at empirically determined intervals.
In such an empirical manner, it is unclear that washing water is properly replenished or exchanged. Therefore, to maintain the quality of development, washing water must be replenished or exchanged frequently, which increases the amount of nonproductive work and the amount of waste water attempts to minimize the frequency of replenishment or exchange of washing water may adversely affect on the quality of development of the photosensitive material.